Photogenerated carrier injection to an n-type copper oxide superconductor

We have fabricated an isotype heterostructure made of an n-type superconductor (Sr0.89Nd0.11)CuO2 film and an n-type SrTiO3:Nb substrate by using the pulsed laser deposition technique and measured the current-voltage and photovoltaic properties under ultraviolet (UV) light irradiation. A large photovoltage of 0.8 V, which is positive to the film, is observed. This means that the photogenerated hole carriers in the SrTiO3:Nb substrate are injected to the film. Under UV light irradiation, the superconducting transition of the film slightly shifts to lower temperature. The effect of the photocarrier injection on the superconducting transition temperature is discussed in terms of a proposed energy level diagram of the (Sr0.89Nd0.11)CuO2/SrTiO3:Nb heterostructure.